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Discussion Starter #1
I've tried cleaning tb and Mas airflow replaced plugs coils are good and have checked for vacuum leaks no luck really bothers me that it only has a little over 87000 on it I shouldn't run rough also there's this rattle in the front end at the beginning of start up and take off but goes away once to speed or at idle
 

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New O2 sensor (front one at least), and replace the MAP sensor.

That's good advice I got from folks here and it worked for me.
 

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Are the cats melted / shit clogged ? Maybe they are newer ones , no info. Yet the rattle from the the front how about the belt and the tensioner wonder when they were replaced.
 

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Are the cats melted / shit clogged ? Maybe they are newer ones , no info. Yet the rattle from the the front how about the belt and the tensioner wonder when they were replaced.
You could take a long screwdriver and carefully press down on the tensioner and see if the rattle goes away. That could mean the rattle is belt and or tensioner related.
There is also PCM fix for rough idle that may or may not be needed on an 08 but it patched my 04 perfectly.
 

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You could take a long screwdriver and carefully press down on the tensioner and see if the rattle goes away. That could mean the rattle is belt and or tensioner related.
There is also PCM fix for rough idle that may or may not be needed on an 08 but it patched my 04 perfectly.


I can think of several better testing methods
...... Who taught you such things.
 

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Discussion Starter #7
When I bought the truck it had a bad cat so the dealer bought a new one and I installed it and gave it good inspection before I installed it but I'll look at the map and o2 advice. I've never touch the belt other than to look at it and it has some fraying but don't think it needs replacd
 

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Discussion Starter #9
It looks okay I mean I drove from my parents house in Idaho to Virginia with it and haven't had any problem with it
 

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Get the new belt before it breaks. Get a new tensioner and idler pulley while you're at it. Swap all 3 parts as preventive maintenance. It will save you a headache from it possibly breaking while on the road.

Just because it has been working, doesn't mean it can't stop working now or soon.
 

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Well okay then.
As long as you understand that belts 'just break'. The warnings received of a bad belt are only cracking and fraying. It won't give you other signs that a replacement is necessary. Such as...oh, something isn't running properly so I should change my belt.

Replacing a belt on the shoulder of a highway isn't as fun as it sounds. Mostly because we don't have a belt in our back pocket, nor tools.

I had a belt break once. Well, it only broke because one of my pulley's seized. haha

Nonetheless, a belt is cheap and will be more of a guarantee that you'll make it back to Idaho without breaking down (as a result of the belt). :)
 

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It can't be idling too bad if the aren't any codes showing.

Belts break at the most inappropriate times. I rather change a belt in my driveway now when it's easy, rather than trying to do it a night along the side of the highway. Belts are cheap and easy to change.

The belt-tensioner is likely the source of the startup noise. Replace it when you put on the new belt.
 

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When addressing the tensioner, replace the whole thing. Some just replace the pulley, but the tensioner spring is more likely the cause. I did the pulley once on a s10. Then had to replace the tensioner a couple months later. It lost its holding power and was causing a rough idle because tensioner was bouncing on the belt causing cycles of slack and over tension.

If I blipped the throttle, the truck would almost die. Easiest way to check is to remove the serpentine belt and start engine to see if it runs smoother. Don't leave it running too long. No coolant flow...
 

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My 08 is rough at start-up as well. New plugs, clean MAF and TB, coils are good, vac lines are fine. It settles down after a few seconds. No CEL, but checking it with Dash Command shows a P0300 Engine Misfire. Internet search suggests all of the above checks, and testing the battery, which I haven't done yet. I'll have it tested and let you all know.
 

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Discussion Starter #16
It idles bad enough to the point that it shakes the vehicle but it is so finicky that sometimes it will run rougher then a Harley then it will calm down and will just have slight shake to it you can feel it more than you can see it on the tach and I'm going to replace the belt and tensioner soon thanks for the advice
 

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Had my battery and alternator checked at Autozone while I was out and about. Battery checked out fine, but Autozone said my alternator was bad. I came home and searched the house over for my voltmeter (I play guitar and use the voltmeter mainly to test wiring and bias tube amps). Checked the battery and alternator myself and then checked the readings against what the Haynes manual stated. Nothing wrong with my battery or alternator. Everything within specs. New plugs, clean MAF, clean TB. Idler arm wobbles a bit, about as much as the video included in the How To Replace tutorial. Guess I'll change it and the belt and see what happens. If that doesn't fix it, I'll start looking at the PCM patch and leak testing.
 

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Discussion Starter #20
I would try replacing the belt first but I would get both at the same time and try and see if the belt has just stretched or just worn the test of that doesn't fix it remove and put the new tensioner on but if it works then take the tensioner back or keep it for future use
 
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